Mule esb introduction

1. Introduction to ESBs:
Mule

2. Agenda
• What is an ESB?
• Java Business Integration (JBI)
• Mule Architecture
• Mule in the Real World

3. Source Material
• [Ric] Mark Richards, “The Role of the
Enterprise Service Bus”, NFJS, Oct 23, 2006.
http://www.infoq.com/presentations/Enterprise-Service-Bus
• [Mul] Mule Architecture Guide.
http://mule.mulesource.org/display/MULE/Architecture+Guide
• September [mule-user archive]

4. Problems Addressed by ESBs
• Integration of existing systems
• Refactorable in real time
• Flexibility to change as requirements change
• Decentralized (service-location transparency)
• Scalable (point solutions to full enterprise)
• Sharing of services across enterprise
• Ability to separate Business Services from
Service Implementations
• Leverages standards

5. Definition(s)
Gartner Group
Giant exercise in Separation of Concerns
[Ric]

6. Definitions (more)
www.datapower.com
[Ric]

7. ESB Features
• Routing
• Message Transformation
• Message Enhancement
• Protocol Transformation
• Service Mapping
 Message Processing
 Process Choreography
 Service Orchestration
 Transaction Management
 Security
[Ric]

8. An ESB Blueprint
General case
Client calls Choreographer Client calls Mediator
vs
[Ric]

9. Java Business Integration (JBI)
• JSR-208 Standard
• Defines service engines (SE – choreographers,
transformers, security, etc) and binding components (BC –
xml, http, etc)
• Concerned with how internal customers (not external
services) interact with service providers
COTS
[Ric]

10. JBI Example
• XSLT – message transformation
• PXE – choreography
• Groovy – scripting
[Ric]

11. JBI Case Study: Service Mix
Service Mix
Binding Components
Service Engines
[Ric]

12. Mule Architecture
[Mule]

13. Mule Flow View
• Channel – a method of connecting between two points (not part of
Mule)
• Connector – a transport provider (e.g., http, jms, soap, smtp, etc)
implementing message receive and message dispatch
• Transformer – converts message structure/format (e.g., http to xml)
• Router – moves messages amongst UMOs and connectors
[Mule]

14. Mule Connector View
http://myapp.com pop3://user@userland.comhttp→xml xml→pop3
myUMO (xml→xml)
[Mule]

15. Mule Transports
• AS400 DQ
• EJB
• E-mail
• File
• FTP
• HTTP
• IMAP
• JDBC
 JMS
 Multicast
 POP3
 Quartz
RMI
 Servlet
 SMTP
 SOAP
 SSL
 Stream
 TCP
 UDP
 VFS
 VM
 WSDL
 XMPP

16. UMO Execution
• Requires a component resolver (e.g., Spring or
Pico) for
– Instantiation of UMOs
– Configuration of UMOs
• Event processing
– Asynchronous
– Synchronous
– Request-Response
[Mule]

17. Mule Programming Model
Application logic
Application glue
Mule glue
[Mule]

18. Mule Routers
[Mule]

19. Selective Consumer (inbound)
• Applies one or more filters to incoming payload, then
branch based on filter
<inbound-router>
<catch-all-strategy
className="org.mule.routing.ForwardingCatchAllStrategy">
<endpoint address="jms://topic:error.topic"/>
</catch-all-strategy>
<router
className="org.mule.routing.inbound.SelectiveConsumer">
<filter expression="msg/header/resultcode = 'success'"
className="org.mule.routing.filters.xml.JXPathFilter"/>
</router>
</inbound-router>

20. Filtering Outbound (outbound)
<outbound-router>
<catch-all-strategy
className="org.mule.routing.ForwardingCatchAllStrategy">
<endpoint="jms://error.queue"/>
</catch-all-strategy>
<router className="org.mule.routing.outbound.FilteringOutboundRouter">
<endpoint address="smtp://ross@muleumo.org"/>
<filter expectedType="java.lang.Exception"
className="org.mule.routing.filters.PayloadTypeFilter"/>
</router>
<router className="org.mule.routing.outbound.FilteringOutboundRouter">
<endpoint address="jms://string.queue"/>
<filter className="org.mule.routing.filters.logic.AndFilter">
<left-filter expectedType="java.lang.String"
className="org.mule.routing.filters.PayloadTypeFilter"/>
<right-filter pattern="the quick brown (.*)"
className="org.mule.routing.filters.RegExFilter"/>
</filter>
</router>
</outbound-router>

21. Nested Router
• Allows synchronous callouts that can be intercepted and routed
<mule-descriptor name="InvokerComponent"
implementation="org.mule.foo.Invoker">
<inbound-router>
<endpoint address="jms://Invoker.in"/>
</inbound-router>
<nested-router>
<binding interface="org.mule.foo.HelloInterface">
<endpoint
address="axis:http://192.168.2.14:81/services/HelloWebComponent?
method=helloMethod" remoteSync="true"/>
</binding>
</nested-router>
<outbound-router>
<router
className="org.mule.routing.outbound.OutboundPassThroughRouter">
<endpoint address="jms://Invoker.out"/>
</router>
</outbound-router>
</mule-descriptor>

22. Dog Days with Mule
• September [mule-user archive]
– How to get a hold of Endpoint object from the
component? {mule}
– Failed to throw UserDefined Exception {jaxws}
– Failed to invoke lifecycle “start” using CXF in
JBOSS {cxf}
– Problem in loading xsd files {mule}
– Problems with RemoteDispatcher {mule}
– Inject MuleClient Singleton with Spring {mule}
– Mule transaction support {mule}

23. ESB Features
• Routing
• Message Transformation
• Message Enhancement
• Protocol Transformation
• Service Mapping
 Message Processing
 Process Choreography
 Service Orchestration
 Transaction Management
 Security
X
X
√
√
√
√
√

24. Take Away Messages
• Mule’s generality results in great flexibility, but at the cost of
great complexity for users
• Mule is the focal point of ambiguity and difficulties with many
standards-based packages
• Mule delivers (to a degree) on:
– Integration, flexibility, decentralized operation, scalability
• Mule doesn’t deliver (so much) on:
– Runtime refactoring, conceptualization